In this case, we describe a 33-year-old man presenting with acute mesenteric ischemia. When we searched for a source of embolism, a giant right atrial mass and patent foramen ovale was discovered. Standard electrocardiography showed signs of an old, silent anteroseptal wall myocardial infarction, confirmed by echocardiography and left ventriculography. Coronary angiography revealed complete occlusion of the left anterior descending artery. The diagnosis of primary antiphospholipid syndrome was confirmed by anticardiolipin antibodies test. Surgical myocardial revascularization along with the resection of the mass and the closure of the patent foramen ovale were performed. Histological examination of the operative specimen showed a thrombus. This is the first reported case presenting with acute paradoxical mesentery embolism accompanying an old myocardial infarction in a young patient with primary antiphospholipid syndrome.